The present invention relates generally to digital X-ray imaging systems. More particularly, the invention relates to a technique for indicating patient position, image orientation or other indicia on a digital radiograph.
Lead, or more generally, radio-opaque markers are commonly used to indicate patient positioning on radiographs. Such markers have long been used for conventional film-based X-ray systems, and hence have continued to be used for more modem digital systems. Such markers generally are placed in a field of view and may include various indicia, such as letters indicating the orientation of patient anatomies visible in the resulting images (e.g., “L” for left and “R” for right), the anatomies themselves, and so forth. Because the markers are placed in the field of view, their image becomes a permanent part of the X-ray image itself. The indicia may also indicate the image orientation, the identity of a technologist who performed an image session, and so forth.
While they provide a simple and robust indication of patient position or image orientation they are not without drawbacks. For example, with the advent of digital radiography and advanced image processing, the presence of such markers can create artifacts in the image. Lead markers located in the exposure field of view of a tomosynthesis acquisition, for example, can cause significant ripple artifacts that can interfere with diagnostic utility of the resulting images.
In other image marking techniques, some digital radiography systems allow the technologist to define the position of a patient relative to the imaging receptor, using a graphical user interface of a computer workstation. The system then automatically places “digital” laterality markers on the appropriate side of the image. However, the user may still have to place other annotations to indicate patient positioning (e.g., “upright”, “supine”, etc.), engendering potential problems. Incorrect annotations are possible because the user is often remote from the patient when applying the digital marker or annotation. Furthermore, placing these other annotations introduces change in workflow of multiple types of radiography systems, leading to inefficiencies and potentially to errors. The wide range of digital manipulations available (e.g., flip, rotate 90 degrees, etc.) provide yet another source of human error.